A plurality of radio communication apparatuses may perform communication using frequencies different from each other without causing mutual interference. A radio communication apparatus that employs the frequency division duplex (FDD) technique, where a frequency band used for transmission signals and a frequency band used for reception signals differ, may perform transmission and reception in parallel.
When a plurality of radio communication apparatuses perform communication using transmission signals with different frequencies, intermodulation occurs at the time when a plurality of transmission signals are reflected off an obstacle, such as a signboard made of metal, and intermodulation distortion waves are caused accordingly. Since the frequency band of the intermodulation distortion waves is dependent on the arrangement of the frequencies of the transmission signals, the frequency band of the intermodulation distortion waves may possibly be included in the frequency band of a reception signal. When the frequency of an intermodulation distortion component and the frequency of a reception signal are equal, to remove the intermodulation distortion component using a filter or the like is difficult and the quality of reception at a radio communication apparatus decreases. It is thus under review to approximately generate an intermodulation distortion signal from a transmission signal and cancel an intermodulation distortion component included in a reception signal using the generated intermodulation distortion signal.
An intermodulation distortion component received at a radio communication apparatus delays, depending on the distance from the radio communication apparatus to the source of the intermodulation distortion component. When the delay amount of an intermodulation distortion signal regenerated in a radio communication apparatus deviates from the delay amount of an intermodulation distortion component actually received, it is difficult to cancel the intermodulation distortion component included in a reception signal even if the regenerated intermodulation distortion signal is combined with the reception signal actually received. Thus, sliding correlation between the intermodulation distortion signal regenerated from a transmission signal and the reception signal actually received is performed. The delay amount that brings the highest correlation value is set for the intermodulation distortion signal regenerated from a transmission signal and the regenerated intermodulation distortion signal is combined with the reception signal. Thus, to cancel an intermodulation distortion component included in a reception signal accurately has been suggested.
Examples of the related art include Japanese National Publication of International Patent Application No. 2015-530787 and Japanese National Publication of International Patent Application No. 2008-532388.